1. Field
This invention relates to the field of incubators, and more particularly to an incubator that is designed to maintain an incubation temperature that is close to room temperature, e.g., between 20 and 25° C.
2. Description of Related Art
Incubators for incubating biological samples, such as human blood samples placed in a bottle or like container, are known in the art. FIG. 1 shows one such incubator 10, marketed by the applicants' assignee bioMerieux, Inc. as the BacT/Alert 3D™ incubation system. The incubator 10 is designed to incubate blood collection bottles 12 which contain a culture medium. The incubator has drawers 14 which pull out from the rest of the incubator to allow the user to insert and remove the bottles 12 from the incubator 10.
The incubator further includes optical sensors (not shown) which read the bottles 12 to determine whether a reaction has occurred between the sample in the bottles and a growth medium in the bottle. The sensors and their method of operation are described in the patent literature, see U.S. Pat. No. 5,164,796. The incubator has an electronics unit 18 positioned at the top of the incubator which receives signals from the optical sensors and which regulates the heater system (not shown) of the incubator which in turn regulates the internal temperature of the incubator. The incubator 10 is typically installed in a biological testing laboratory, e.g., located in a hospital, clinic or other site, and placed on the laboratory bench 20.
In the microbiology testing industry, there are generally two distinct market segments: biopharma and food. These two segments have unique microbiological testing and incubation needs. In particular, the biopharma segment closely follows worldwide Pharmacopoeia methods, which includes microbiological testing and incubation of samples at two temperature ranges: 30-35° C. and 20-25° C. In comparison, the food and other clinical users primarily set their incubators at 36 or 37° C.
The current BacT/ALERT 3D incubator 10 of FIG. 1 is designed to perform at an incubation temperature of 7° C. above ambient to 45° C. When placed in a normal lab environment (ambient temperature approximately 20-22° C.), the temperature differential is sufficiently large that the incubator can reliably incubate within the 30-35° C. incubation range. However, under normal laboratory working conditions in which the laboratory and incubator is maintained in a room temperature (20-22° C.) ambient environment, some incubators are not capable of maintaining a stable incubation range of 20-25° C. Simply leaving the specimen to be incubated out on the laboratory bench at “room temperature” is of course not acceptable, as the environment is not reliably temperature controlled (e.g., a window may be left open, the air conditioning system may not work properly, the heating system may be turned down at night or over the weekend to save energy, etc.).
In order for some incubators to work properly and maintain the 20-25° C. (nominal 22.5° C.) incubation range, in the past the entire incubator is moved to a walk-in environmental chamber which maintains an ambient environment of approximately 13° C. or less. However, this approach does not provide an efficient work environment, because the walk-in environmental chamber is typically not conveniently located, e.g., it is down the hall or on another floor. Moreover, many larger facilities have many incubators such as the incubator 10 of FIG. 1. The walk-in environmental chamber is typically in a separate location away from the other incubators, thus making use of the incubators in the environmental chamber more inconvenient and inefficient.
An alternative approach that has been considered is to cool the entire laboratory space where the incubators are located down to say 10-13 degrees C. However, this is not a comfortable work environment for laboratory technicians, as they have to bundle up to stay warm and contend with working with cold hands.
Organon Teknika, the company which originally designed the incubator module 10 shown in FIG. 1, at one time developed an incubation instrument known as the “Kool Boy” to satisfy the need for incubation at cooler temperature than 30° C. The design included a cooling unit placed in a custom cart with an incubator on top. The cooling unit was a window air conditioner. The air was drawn in from the front of the cart and the cool air exited out duct work along the back edge of the cart. The incubator rear panel was removed and replaced with duct work that attached to the top rear of the cart. The cool air from the cooling unit blew directly into the incubator. Firmware within the incubator controlled the temperature of the airflow. This unit was considered to be too noisy for the laboratory environment due to the high blower RPMs. The 220 VAC power supply the unit required was not easily adaptable to most laboratories either. The product was a commercial failure for these and other reasons, and supposedly only 1 or 2 instruments were ever sold.
The incubation system and apparatus of this invention solves this problem of providing incubators which can properly and reliably maintain an incubation temperature at or near room temperature (20-25° C.), while allowing laboratory workers to work in a normal laboratory environment at room temperature and allow all the incubators to be maintained in the same vicinity by avoiding the use of special environmental chambers and resulting inefficiencies. This invention also overcomes the many deficiencies that the Kool Boy instrument suffered from.